Platinum conical ultramicroelectrodes

Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712-0165, USA 

Conical-shaped ultramicroelectrodes (UMEs) are of special interest in connection with the imaging of surfaces, in kinetic studies, in probing thin films, and in probing minute environments, such as single cells. The most common fabrication procedure is by the etching of platinum wire or carbon fibers followed by coating with an insulating material except at the apex of the electrode. In this section, the fabrication of both blunt and sharp conical electrodes are discussed. 

Pt conical UMEs are constructed from 25 pm or 50 pm diameter Pt or Pt-Ir wires. A 2-cm length of Pt wire is connected to a conductive wire with silver epoxy (Epotek, H20E, Epoxy Technology, Inc., Billerica, MA). The ensemble is then enclosed in a glass capillary, which 

The etched conical Pt tips are then coated with an insulating material, except at the apex of the tip. A number of coating procedures have been reported in the literature. 

Once fabricated, the conical electrodes can be characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), steady-state voltammetry (SSV), and scanning electrochemical microscopy (SECM) (see Chapter 12). 

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